GitLab

The generic Makefile.kasan propagates CONFIG_KASAN_SHADOW_OFFSET into
KASAN_SHADOW_OFFSET, but only does so for CONFIG_KASAN_GENERIC.

Since commit:

  6bd1d0be ("arm64: kasan: Switch to using KASAN_SHADOW_OFFSET")

... arm64 defines CONFIG_KASAN_SHADOW_OFFSET in Kconfig rather than
defining KASAN_SHADOW_OFFSET in a Makefile. Thus, if
CONFIG_KASAN_SW_TAGS && KASAN_INLINE are selected, we get build time
splats due to KASAN_SHADOW_OFFSET not being set:

| [mark@lakrids:~/src/linux]% usellvm 8.0.1 usekorg 8.1.0  make ARCH=arm64 CROSS_COMPILE=aarch64-linux- CC=clang
| scripts/kconfig/conf  --syncconfig Kconfig
|   CC      scripts/mod/empty.o
| clang (LLVM option parsing): for the -hwasan-mapping-offset option: '' value invalid for uint argument!
| scripts/Makefile.build:273: recipe for target 'scripts/mod/empty.o' failed
| make[1]: *** [scripts/mod/empty.o] Error 1
| Makefile:1123: recipe for target 'prepare0' failed
| make: *** [prepare0] Error 2
...